1. Field of the Invention
Methods consistent with the present invention relate to allocating resource among mobile stations in a distribution communication network. More particularly, the methods consistent with present invention relate to allocating resources among mobile stations in a distribution communication network, according to which a mobile station perceives the existence of another mobile station through a resource allocation time slot, and without having to communicate with a sensor node, and if perceiving another mobile station, the mobile station allocates time slot resources in a manner of avoiding overlapping with time slot resources of the other mobile stations, and performs location measurement or media access and reception of service from the sensor node through the allocated time slot resource.
2. Description of the Related Art
Wireless Personal Area Network (WPAN), which is one of the short distance communications networks, connects computers with peripherals, mobile terminals and electronic appliances within the distance of 10 m and enables two-way communications. WPAN is the concept distinct from the Local Area Network (LAN) or Wide Area Network (WAN). WPAN is not an infra-structured network, but a small, personal version of a wireless communication network, which can be realized with low cost and power consumption. Applications of WPAN include a home network.
IEEE 802.15.3 Task Group (TG) is developing standards of WPAN Technology. According to IEEE 802.15.3, high-speed data transmission of 11 to 55 Mbps is possible with low power consumption, within the limited data transmission range of 10 m. The IEEE 802.15.3a group is developing a standard of IEEE 802.15.3 to standardize a WPAN system using an UltraWide Band (UWB) system. Under IEEE 802.15.3, physical layer (PHY) is upgraded to a high-speed of 100 Mbps level, and can be applied to the areas such as multimedia transmission of wireless motion pictures in short distance communications including a home network.
A piconet is a basic unit of WPAN. The piconet is the network of one or more mobile stations which share the same network identifier with a single piconet coordinator (PNC). The piconet coordinator forms a piconet by transmitting a beacon, provides basic communication timing, and provides the mobile stations of the piconet under its management with the wireless communication services such as Quality of Service (QoS), synchronization, power save mode and media access control (MAC).
According to IEEE 802.15.3, a piconet is generated whenever it is necessary. A plurality of mobile stations of the piconet independently share a single medium in a peer-to-peer way and communicates in a multihop method. Such piconet is generally called an ad-hoc network.
“Multihop” refers to a communication between the respective mobile stations of an ad-hoc network, in which a packet from a sender arrives at a destination node via a plurality of mobile devices which operate as both a host and a router. Because the wireless transmission range is limited to a maximum of 10 m in the piconet, packets are sometimes not transmitted directly from the sender to the destination.
Because a plurality of mobile stations communicate with each other via one medium in the piconet, access to the respective mobile stations needs be controlled in proper timing in the communication of the respective mobile stations, so as to prevent collision of communication.
Accordingly, a technique is required to recognize the location of the mobile stations within the communication range of short distance communications. As a system and a method of recognizing the location of one mobile station, one suggestion is that a mobile station transmits an RF signal and ultrasonic signal to a plurality of sensors attached to a ceiling, and the sensors receiving the signal calculate distances using the differences of arrival time based on the speed differences of the RF signal and ultrasonic signal and transmit the calculated result to the mobile station.
However, the problem arises when a plurality of mobile stations request measurement of location at the same time, in which signals for location measurement frequently collide. In this case, location cannot be accurately measured. Accordingly, a method to perform the location measurement in the short-distance communication environment of a plurality of mobile stations without collisions of location measurement signals is needed.